The internet is vastly changing the way that businesses and individuals communicate. Businesses typically have the resources to gain access to high-speed, large bandwidth connections to the internet. However, this has not been the case with individuals due to the complexity and expense. CATV networks have begun to fill this void and provide high-speed large bandwidth access to the internet. With the internet becoming more popular for many consumer applications, the use of a CATV network to access the internet has become even more paramount. Accordingly, as the amount of data being transmitted over a CATV network increases with user demand, it is critical that CATV networks be configured to meet those demands.
Current CATV settop terminals utilize dedicated data channels, (such as a service data channel), and the vertical blanking interval (VBI) of an inband video signal in order to send data. The data channels are dedicated to data transmission and are not associated with any inband video channels. Unlike an inband video channel, which originates at a content provider, the dedicated data channels are out-of-band channels which originate at the headend of the CATV system and provide information specific to the CATV system, such as data for the video programming guide, settop terminal addressable data and other control information. Although dedicated data channels provide an effective method for transmitting data to a settop terminal, they force a CATV network provider to reserve a portion of the CATV spectrum solely for data transmission.
A second method for transmitting data is to transmit the data within one of the lines of the VBI, which is part of each frame of an inband video signal. FIG. 1 shows a prior art use of the VBI to transmit data. Embedded within each inband video signal sent over the inband channel is specific information. The complete video picture, called a frame, is made up of two fields each containing 262xc2xd horizontal scan lines, (for an NTSC system). After each field of 262xc2xd horizontal lines is scanned, the scanning beam returns to the top of the screen to begin scanning of the next field. The retrace time is called the VBI. During the VBI, no program video information is included in the composite video signal. The VBI lasts for 21 horizontal lines (or 1333.5 xcexcS), each line containing a number of bits of information. The VBI may include special reference signals that are located on selected lines of the VBI. Several common signals located in the VBI include the vertical interval test signal on lines 17 and 18, the vertical interval reference signal on line 19, and the closed caption signal on line 21. The VBI, however, is unable to transmit the large amounts of data that are currently required by today""s applications.
Generally, current teletext receivers are only capable of receiving a single data format or a single video standard. Different standards typically require different hardware or different hardware components. Therefore, multiple simultaneous standards are not generally supported. Also, the features that inband data receivers provide may be limited to simple data packet reception with little or no data filtering. For example, packet filtering requires intervention from the main system processor.
Accordingly, there exists a need for a system which transmits large amounts of data to support today""s data applications and which also provides a CATV network operator with flexibility in managing the network spectrum.
The present invention comprises a system for receiving high-speed data within a CATV video signal over a CATV network. The system comprises a data detector for receiving the CATV video signal and for extracting the data from said CATV video signal; a data processor for determining the destination address of the data; and a memory, for selectively storing data until required by the data processor. The system is adaptable to different video standards and data formats.